While a variety of biocidal polymers (e.g., quaternary ammonium salts, phosphonium materials, halogenated sulfonamides, and biguanides—see Trends Polym. Sci. 4:364 (1996)) have been synthesized and tested for biotidal activity, a relatively new class known as cyclic N-halamines has been shown to have far superior properties including biocidal efficacy, long-term stability, and rechargability once the efficacy has been lost. Such a material is poly-1,3-dichloro-5-methyl-5-(4′-vinylphenyl)hydantoin which is an inexpensive derivative of poly-styrene, and which was first described in U.S. Pat. No. 5,490,983, now incorporated herein by reference. Subsequent disclosures of its biocidal properties for use in disinfecting applications for water filters have recently occurred [see Ind. Eng. Chem. Res. 33:168 (1994); Water Res. Bull. 32:793 (1996); Ind. Eng. Chem. Res. 34:4106 (1995); J. Virolog. Meth. 66:263 (1997); Trends in Polym. Sci. 4:364 (1996); Water Cond. & Pur. 39:96 (1997)]. The polymer is effective against a broad spectrum of pathogens including Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Candida albicans, Klebsiella terrigena, Legionella pneumophila and rotavirus, among others, causing large log reductions in contact times of the order of a few seconds in water disinfectant applications. Furthermore, it is effective at pH values at least in the range 4.5 to 9.0 and at temperatures at least in the range 4° C. to 37° C., and it is capable of action even in water containing heavy chlorine demand caused by bioburden.
This biocidal polymer is insoluble in water and organic compounds and will thus not migrate in liquid media. It is stable for long periods of time in dry storage (a shelf life of at least one year at ambient temperature) and can be produced on an industrial scale. Furthermore, all evidence obtained to date suggests that the material is non-toxic and non-sensitizing to humans and animals upon contact.
A variety of microorganisms such as certain bacteria, fungi, and yeasts are capable of aiding the decomposition of bodily fluids such as urine and blood, or in the formation of biofilms, which produce undesirable odors in otherwise useful commercial products. For example, bacteria such as Bacterium ammoniagenes and Proteus mirabilis are known to accentuate the decomposition of urea to form noxious ammonia gas through a urease enzyme catalysis mechanism (see for example U.S. Pat. No. 5,992,351). The same polymer mentioned above (poly-1,3-dichloro-5methyl-5-(4′-vinylphenyl)hydantoin) has been shown to be effective at inactivating Proteus mirabilis and thus minimizing the undesirable odor created by ammonia gas (U.S. patent application Ser. No. 09/685,963, herein incorporated by reference). Also, the polymer is insoluble in bodily fluids so as not to migrate to skin surfaces, rendering it useful, in applications such as disposable diapers, incontinence pads, bandages, sanitary napkins, and pantiliners.
However, the composition of poly-1,3-dichloro-5-methyl-5-(4′-vinylphenyl)hydantoin and use as a biocide for water-filter applications described in U.S. Pat. No. 5,490,983 and its use for odor control described in U.S. patent application Ser. No. 09/685,963 involved a form of the material which was a fine powder with a noticeable chlorine odor. In this form the material exhibited a tendency to cause excessive back-pressure in a water filtration application thereby slowing down flow rates, and the fine particles could potentially be aerosolized in an industrial setting causing concern for workers handling the material. Thus it was deemed necessary to find a method of creating the material as larger particles with less chlorine outgassing, while maintaining its biocidal efficacy.